The set of complex numbers is represented by C, and the set of real numbers is represented by R. Obviously, R is the proper subset of C, and the set of complex numbers is out of order, so the order of size cannot be established. The value of the positive square root of the square sum of the real part and imaginary part of a complex number is called the module of the complex number, which can be written as ∣z∣.
Generally, numbers in the form of z=a+bi are called complex numbers, where A is called the real part, B is called the imaginary part, and I is called the imaginary part. When the imaginary part is equal to zero, this complex number can be regarded as a real number; When the imaginary part of z is not equal to zero and the real part is equal to zero, z is often called pure imaginary number. Complex number field is an algebraic closure of real number field, that is, any polynomial with complex coefficients always has roots in complex number field.
Extended data:
Letters representing complex sets:
N in mathematics: nonnegative integer set or natural number set {0, 1, 2, 3, …}
N* or N+: positive integer set {1, 2,3, …}
Z: integer set {…,-1, 0, 1, …}
Q: Rational number set
Q+: Set of Positive Rational Numbers
Q-: set of negative rational numbers
R: set of real numbers (including rational numbers and irrational numbers)
R+: positive real number set
R-: negative real number set
C: complex set
Baidu Encyclopedia -C (Mathematical Symbol)
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